An outdoor unit for an air conditioner includes a housing of a substantially rectangular parallelepiped shape. A compressor, an outdoor heat exchanger (hereinafter referred to as a heat exchanger), and a fan are installed in the housing. A partition is interposed between a section provided with the compressor and a section provided with the heat exchanger and the fan. The heat exchanger is disposed in a substantially L-shape along a lateral side of the housing. A bottom plate forming a bottom portion of the housing is provided with a drainage hole penetrating the bottom plate, so that water collected in the housing is discharged from the drainage hole. For this reason, the drainage hole is located at the lowest position of the bottom plate. The bottom plate of the section provided with the heat exchanger and the fan has a drainage conduit connected to the drainage hole, so that the water in the housing is guided by the drainage groove to flow to the drainage hole. Further, loading shelves having a predetermined height from the position of the drainage hole in its vertical direction protrude inwardly from the lateral face of the housing at plural portions, and the heat exchanger is placed on the loading shelves. For this reason, lower ends of the heat exchanger are positioned at a position higher than the drainage conduit. In this way, the water collected in the outdoor unit is discharged outwardly from the outdoor unit, and the lower ends of the heat exchanger and the fan are not submerged in the water flowing along the drainage conduit.
The heat exchanger of the outdoor unit for the air conditioner is, for example, a fin-tube heat exchanger including thin plate-like fins made of aluminum and arranged horizontally, and heat exchange tubes penetrating the fins, in which when refrigerant flowing in the heat exchanger tubes is heat-exchanged with external air from the fan, a contact area between the heat exchanger tubes and the air is increased by the fins to improve a heat exchange efficiency.
At a heating operation to heat an inside of a room, the cold refrigerant flows in the heat exchanger tubes of the heat exchanger, and vapor in the external air is cooled in the heat exchange tubes to become dew water which is adhered to the heat exchange tubes and perimeters of fins. The dew water flows down along the heat exchange tubes and the fins, and then drips onto the bottom plate. The dew water is known as drain water, and flows to the drainage hole through the drainage conduit provided in the bottom plate to be discharged from the outdoor unit. In a case where the drain water is not smoothly led to the drainage hole, the drain water is locally collected around the heat exchanger or the bottom plate, which leads to an adverse effect on the operation of the fan or the heat exchanger.
In particular, in cold climates, the drain water becomes frost and causes frost formation on the heat exchanger tubes or fins. When the frost adhered to the heat exchanger is melted by defrost operation which is regularly or occasionally performed, a large volume of water flows down to the bottom plate. The large volume of water is not discharged outwardly from the outdoor unit, but remains on the bottom plate of the outdoor unit which may be frozen. If the ice grows around the heat exchanger or the fan, it is disruptive to rotation of the fan, or the heat exchanger tubes of the heat exchanger are deformed by application of the pressure from its perimeter due to the ice.
Several drainage structures capable of guiding the drain water to the drainage hole have been proposed in the outdoor unit for the air conditioner. For example, related-art discloses an outdoor unit in which loading shelves on which the heat exchanger is partially loaded, and a drainage conduit are disposed on a bottom plate of a housing to be adjacent to each other, and the bottom plate of the heat exchanger is provided with a gutter communicating the heat exchanger loading shelves and the drainage conduit at one side of the heat exchanger (e.g., see JP-A-2005-188837 (FIGS. 1 and 2)).
According to the outdoor unit for the air conditioner of the related art, the loading shelves are installed near an edge of the bottom plate, an about half portion (back face side) of the heat exchanger is loaded on the loading shelves, and the remaining portion (front face side) of the heat exchanger in a width direction (width direction of fin) is positioned near a center of the bottom surface. In addition, the bottom plate of the lower portion of the heat exchanger is provided with the gutter inclining downward toward the drainage conduit, and the heat exchanger loading shelves at the rear side of the heat exchanger and the drainage conduit are communicated each other. With the configuration, the drain water generated from the front side of the heat exchanger directly drips onto the drainage groove, while the drain water generated from the rear side of the peripheral portion and flowing down to the heat exchanger loading shelves is usually led to the drainage conduit through the gutter.